Endothelium-derived relaxing factor (EDRF) is a labile humoral agent which is part of a cascade of interacting agents involved in the relaxation of vascular smooth muscle. EDRF is thus important in the control of vascular resistance to blood flow and in the control of blood pressure. Some vasodilators act by causing EDRF to be released from endothelial cells. (See Furchgott, Ann. Rev. Pharmacol. Toxicol. 24, 175-197, 1984.) Recently, Palmer et al., have shown that EDRF is identical to the simple molecule, nitric oxide, NO. (Nature 317, 524-526, 1987.) It has been hypothesized for years that many nitrovasodilators, which mimic the effect of EDRF, like glyceryl trinitrate, amyl nitrite, NaNO.sub.2 and sodium nitroprusside (SNP), do so by virtue of their conversion to a common moiety, namely NO, which is also a vasodilator. (See Kruszyna et al., Tox. & Appl. Pharmacol.,91, 429-438, 1987; Ignarro, FASEB J. 3, 31-36, 1989, and Ignarro et al., J. Pharmacol. Exper. Theraputics 218(3), 739-749, 1981.) It has now been discovered that compounds containing the N-oxy-N-nitrosoamine group, N.sub.2 O.sub.2.sup.- (also known as the N-nitrosohydroxylamine group) of the structure: ##STR2## and wherein the compound decomposes under physiological conditions to release NO, are potent anti-hypertensives. The compounds are useful for treating cardiovascular disorders in which lowering the blood pressure has a beneficial result. It is believed that these compounds function by releasing NO in the blood after injection. Alston et al. have shown that NO is generated by in vitro enzymatic oxidation of N-hydroxy-N-nitrosoamines (J. Biol. Chem. 260(7), 4069-4074, 1985) and Kubrina et al. have shown in vivo formation of nitrogen oxide upon injection with ammonium N-oxy-N-nitrosoaminobenzene (cupferron) into experimental animals( Izvestiia Akademii Nauk SSSR Seriia Biologicheskaia 6, 844-850, 1988).
While these compounds are, for the most part, known, there is no suggestion in the prior art that they are anti-hypertensive, indeed, there is no suggestion in the prior art that this general class of compounds has any pharmaceutical use (except for alanosine and dopastin, see below). They are described by Drago in "Free Radicals in Inorganic Chemistry" Advances in Chemistry Series, Number 36, American Chemical Society, Wash. DC, 1962, pages 143-149, which is incorporated by reference in its entirety. The reference is of a theoretical nature and mentions no utility whatsoever. Danzig et al., U.S. Pat. No. 3,309,373, discloses many of the compounds of formula I. Danzig teaches many possible utilities of his compounds, including their use as curing agents in rubber manufacture, antiknock additives for gasoline, indicator dyes, explosives, corrosion inhibitors and as fungicides for agriculture. Danzig et al. is incorporated by reference in its entirety. Wiersdorff et al (Chemical Abstracts 77:48034f, 1972) discloses that compounds of formula I, wherein J is a substituted phenyl, are useful as complexing agents and as fungicides. Fujitsuka et al. (Chemical Abstracts 82:31108p, 1975) discloses that compounds wherein J is phenyl, p-hydroxyphenyl and cyclohexyl are useful as polymerization inhibitors. Japanese patent JP 87017561 B, 4/18/87, discloses that the compounds wherein J is an aromatic hydrocarbon radical or sulfite (.sup.- O.sub.3 S--) are antibiotics for nitrifying bacteria and are added to industrial waters to control the bacteria. This patent does not teach the in vivo use of the compounds. Massengale, U.S. Pat. No. 2,635,978, discloses that compounds wherein J is optionally substituted phenyl are useful as fungicides for treating seeds, plants and fruits. Metzger et al., U.S. Pat. No. 2,954,314, discloses that compounds wherein J is an aliphatic, arylaliphatic or cycloaliphatic group are useful as fungicides for the external treatment of plants, leather, paper etc. Both Massengale and Metzger et al. are incorporated by reference in their entirety. None of the references cited above teach that compounds of formula I are antihypertensives, indeed none of these references teach any in vivo pharmaceutical utility of these compounds. There are two compounds that have in vivo pharmaceutical utility and contain the N-oxy-N-nitrosoamine moiety. These are alanosine, a potential anticancer drug with the structure ##STR3## and dopastin, a dopamine beta-hydroxylase inhibitor of structure ##STR4## These compounds were not known to be antihypertensive previously. The applicant has disclosed the antihypertensive utility of the compounds wherein J is a primary or secondary amine in U.S. Pat. Nos. 4,954,526 and 5,039,705 respectively.